OBJECTIVE: Poly(lactide-co-glycolide) (PLGA) nanoparticles are promising materials for the development of new drug-releasing systems. The purpose of this study was to evaluate the in vivo retention time of materials loaded in nanoparticles as compared with that of the material alone by in vivo imaging in nude mice. MATERIALS AND METHODS: Mice (n = 20) were injected with 0.1 mL fluorescent material 1,1′-dioctadecyl-3,3,3′,3′ tetramethylindotricarbocyanine iodide (DiR)-loaded PLGA nanoparticles (200 nm) into the right paraspinal muscle, and the same volume of pure DiR solution was injected into the left paraspinal muscle. Fluorescence images were obtained using an in vivo optical imaging system. Fluorescent images were taken 1 day after the injection, and seven more images were taken at 1-week intervals. Image analysis was done with ImageJ program, and one region of interest was chosen manually, which corresponded to the highest signal-intensity area of fluorescence signal intensity. RESULTS: After 7 weeks, 12 mice showed a right-sided dominant signal, representing the DiR loaded PLGA nanoparticles; 5 mice showed a left-side dominant signal, representing the free DiR solution; and 3 mice showed no signal at all beginning 1 day after the injection. During the 7-week period, the mean signal intensities of the free DiR solution and DiR-loaded PLGA nanoparticles diverged gradually. On day 1, the mean signal intensity of free DiR solution was significantly higher than that of DiR-loaded PLGA (p < 0.001). Finally, by week 7, DiR-loaded PLGA express significantly high signal intensity compared with free DiR solution (p = 0.031). CONCLUSION: The results of the current study suggested that therapeutic agents bound to PLGA nanoparticles may exhibit prolonged retention times.
Animals ; Fluorescence ; Mice* ; Mice, Nude ; Nanoparticles* ; Optical Imaging ; Paraspinal Muscles ; Polyglactin 910*

A 17-year-old man was referred to our hospital because of dizziness and mild dyspnea. He had a history of partial thyroidectomy due to benign mass when he was 10 year-old. His conjunctiva was anemic and acral keratosis was noted. He had a goiter and a previous surgical scar on the anterior neck just below the thyroid cartilage. Blood counts were as follows; Hb was 4.3 g/dL, WBC 5,500/mm3, PLT 366,000/ mm3. Esophagogastroduodenoscopy and colonoscopy showed esophageal acanthosis and numerous variable sized polyps in the stomach, duodenum and colon. The small bowel series showed numerous polypoid lesions in the entire small bowel. Gastric polyps revealed hamartoma and colon polyps revealed inflammatory polyp with lymphoid hyperplasia by pathologic examination. Thyroid ultrasonograph showed multiple nodules and cysts and I131 scintigraphy showed multiple cold and hot nodules in his remnant thyroid gland. We diagnosed the patient as Cowden's syndrome.
Adolescent ; Child ; Cicatrix ; Colon ; Colonoscopy ; Conjunctiva ; Dizziness ; Duodenum ; Dyspnea ; Endoscopy, Digestive System ; Goiter ; Hamartoma ; Hamartoma Syndrome, Multiple* ; Humans ; Hyperplasia ; Keratosis ; Neck ; Polyps ; Radionuclide Imaging ; Stomach ; Thyroid Cartilage ; Thyroid Gland ; Thyroid Nodule ; Thyroidectomy